/*
 * Swipe 2.0
 *
 * Brad Birdsall
 * Copyright 2013, MIT License
 *
*/

function Swipe(container, options) {

	"use strict";

	// utilities
	var noop = function() {}; // simple no operation function
	var offloadFn = function(fn) { setTimeout(fn || noop, 0) }; // offload a functions execution
	
	// check browser capabilities
	var browser = {
		addEventListener: !!window.addEventListener,
		touch: ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch,
		transitions: (function(temp) {
			var props = ['transformProperty', 'WebkitTransform', 'MozTransform', 'OTransform', 'msTransform'];
			for ( var i in props ) if (temp.style[ props[i] ] !== undefined) return true;
			return false;
		})(document.createElement('swipe'))
	};

	// quit if no root element
	if (!container) return;
	var element = container.children[0];
	var slides, slidePos, width;
	options = options || {};
	var index = parseInt(options.startSlide, 10) || 0;
	var speed = options.speed || 300;
	options.continuous = options.continuous ? options.continuous : true;

	function setup() {
		// cache slides
		slides = element.children;

		// create an array to store current positions of each slide
		slidePos = new Array(slides.length);

		// determine width of each slide
		width = container.getBoundingClientRect().width || container.offsetWidth;

		element.style.width = (slides.length * width) + 'px';

		// stack elements
		var pos = slides.length;
		while(pos--) {

			var slide = slides[pos];

			slide.style.width = width + 'px';
			slide.setAttribute('data-index', pos);

			if (browser.transitions) {
				slide.style.left = (pos * -width) + 'px';
				move(pos, index > pos ? -width : (index < pos ? width : 0), 0);
			}

		}

		if (!browser.transitions) element.style.left = (index * -width) + 'px';
		container.style.visibility = 'visible';
	}

	function prev() {
		if (index) slide(index-1);
		else if (options.continuous) slide(slides.length-1);
	}

	function next() {
		if (index < slides.length - 1) slide(index+1);
		else if (options.continuous) slide(0);
	}

	function slide(to, slideSpeed) {

		// do nothing if already on requested slide
		if (index == to) return;
		if (browser.transitions) {
			var diff = Math.abs(index-to) - 1;
			var direction = Math.abs(index-to) / (index-to); // 1:right -1:left
			while (diff--) move((to > index ? to : index) - diff - 1, width * direction, 0);
			move(index, width * direction, slideSpeed || speed);
			move(to, 0, slideSpeed || speed);
		} else {
			animate(index * -width, to * -width, slideSpeed || speed);
		}

		index = to;
		offloadFn(options.callback && options.callback(index, slides[index]));
	}

	function move(index, dist, speed) {
		translate(index, dist, speed);
		slidePos[index] = dist;
	}

	function translate(index, dist, speed) {
		var slide = slides[index];
		var style = slide && slide.style;

		if (!style) return;

		style.webkitTransitionDuration = 
		style.MozTransitionDuration = 
		style.msTransitionDuration = 
		style.OTransitionDuration = 
		style.transitionDuration = speed + 'ms';

		style.webkitTransform = 'translate(' + dist + 'px,0)' + 'translateZ(0)';
		style.msTransform = 
		style.MozTransform = 
		style.OTransform = 'translateX(' + dist + 'px)';
	}

	function animate(from, to, speed) {
		// if not an animation, just reposition
		if (!speed) {
			element.style.left = to + 'px';
			return;
		}
		
		var start = +new Date;
		var timer = setInterval(function() {
			var timeElap = +new Date - start;
			if (timeElap > speed) {
				element.style.left = to + 'px';
				if (delay) begin();
				options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);
				clearInterval(timer);
				return;
			}
			element.style.left = (( (to - from) * (Math.floor((timeElap / speed) * 100) / 100) ) + from) + 'px';
		}, 4);

	}

	// setup auto slideshow
	var delay = options.auto || 0;
	var interval;

	function begin() {
		interval = setTimeout(next, delay);
	}

	function stop() {
		delay = 0;
		clearTimeout(interval);
	}


	// setup initial vars
	var start = {};
	var delta = {};
	var isScrolling;      

	// setup event capturing
	var events = {
		handleEvent: function(event) {
			switch (event.type) {
				case 'touchstart': this.start(event); break;
				case 'touchmove': this.move(event); break;
				case 'touchend': offloadFn(this.end(event)); break;
				case 'webkitTransitionEnd':
				case 'msTransitionEnd':
				case 'oTransitionEnd':
				case 'otransitionend':
				case 'transitionend': offloadFn(this.transitionEnd(event)); break;
				case 'resize': offloadFn(setup.call()); break;
			}
			if (options.stopPropagation) event.stopPropagation();
		},
		start: function(event) {
			var touches = event.touches[0];
			// measure start values
			start = {
				// get initial touch coords
				x: touches.pageX,
				y: touches.pageY,
				// store time to determine touch duration
				time: +new Date
			};
			
			// used for testing first move event
			isScrolling = undefined;

			// reset delta and end measurements
			delta = {};

			// attach touchmove and touchend listeners
			element.addEventListener('touchmove', this, false);
			element.addEventListener('touchend', this, false);

		},
		move: function(event) {
			// ensure swiping with one touch and not pinching
			if ( event.touches.length > 1 || event.scale && event.scale !== 1) return
			if (options.disableScroll) event.preventDefault();

			var touches = event.touches[0];

			// measure change in x and y
			delta = {
				x: touches.pageX - start.x,
				y: touches.pageY - start.y
			}

			// determine if scrolling test has run - one time test
			if ( typeof isScrolling == 'undefined') {
				isScrolling = !!( isScrolling || Math.abs(delta.x) < Math.abs(delta.y) );
			}

			// if user is not trying to scroll vertically
			if (!isScrolling) {
				// prevent native scrolling 
				event.preventDefault();
				// stop slideshow
				stop();
				// increase resistance if first or last slide
				delta.x = 
					delta.x / 
						( (!index && delta.x > 0               // if first slide and sliding left
							|| index == slides.length - 1        // or if last slide and sliding right
							&& delta.x < 0                       // and if sliding at all
						) ?                      
						( Math.abs(delta.x) / width + 1 )      // determine resistance level
						: 1 );                                 // no resistance if false
				
				// translate 1:1
				translate(index-1, delta.x + slidePos[index-1], 0);
				translate(index, delta.x + slidePos[index], 0);
				translate(index+1, delta.x + slidePos[index+1], 0);
			}

		},
		end: function(event) {
			// measure duration
			var duration = +new Date - start.time;

			// determine if slide attempt triggers next/prev slide
			var isValidSlide = 
						Number(duration) < 250               // if slide duration is less than 250ms
						&& Math.abs(delta.x) > 20            // and if slide amt is greater than 20px
						|| Math.abs(delta.x) > width/2;      // or if slide amt is greater than half the width

			// determine if slide attempt is past start and end
			var isPastBounds = 
						!index && delta.x > 0                            // if first slide and slide amt is greater than 0
						|| index == slides.length - 1 && delta.x < 0;    // or if last slide and slide amt is less than 0
			
			// determine direction of swipe (true:right, false:left)
			var direction = delta.x < 0;

			// if not scrolling vertically
			if (!isScrolling) {

				if (isValidSlide && !isPastBounds) {

					if (direction) {
						move(index-1, -width, 0);
						move(index, slidePos[index]-width, speed);
						move(index+1, slidePos[index+1]-width, speed);
						index += 1;
					} else {
						move(index+1, width, 0);
						move(index, slidePos[index]+width, speed);
						move(index-1, slidePos[index-1]+width, speed);
						index += -1;
					}
					options.callback && options.callback(index, slides[index]);

				} else {
					move(index-1, -width, speed);
					move(index, 0, speed);
					move(index+1, width, speed);
				}

			}
			// kill touchmove and touchend event listeners until touchstart called again
			element.removeEventListener('touchmove', events, false)
			element.removeEventListener('touchend', events, false)
		},
		transitionEnd: function(event) {

			if (parseInt(event.target.getAttribute('data-index'), 10) == index) {
				if (delay) begin();
				options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);
			}

		}

	}

	// trigger setup
	setup();

	// start auto slideshow if applicable
	if (delay) begin();

	// add event listeners
	if (browser.addEventListener) {
		
		// set touchstart event on element    
		if (browser.touch) element.addEventListener('touchstart', events, false);

		if (browser.transitions) {
			element.addEventListener('webkitTransitionEnd', events, false);
			element.addEventListener('msTransitionEnd', events, false);
			element.addEventListener('oTransitionEnd', events, false);
			element.addEventListener('otransitionend', events, false);
			element.addEventListener('transitionend', events, false);
		}

		// set resize event on window
		window.addEventListener('resize', events, false);
	} else {
		window.onresize = function () { setup() }; // to play nice with old IE
	}

	// expose the Swipe API
	return {
		setup: function() {
			setup();
		},
		slide: function(to, speed) {
			slide(to, speed);
		},
		prev: function() {
			// cancel slideshow
			stop();
			prev();
		},
		next: function() {
			stop();
			next();
		},
		getPos: function() {
			// return current index position
			return index;
		},
		kill: function() {
			// cancel slideshow
			stop();
			// reset element
			element.style.width = 'auto';
			element.style.left = 0;
			// reset slides
			var pos = slides.length;
			while(pos--) {
				var slide = slides[pos];
				slide.style.width = '100%';
				slide.style.left = 0;
				if (browser.transitions) translate(pos, 0, 0);
			}

			// removed event listeners
			if (browser.addEventListener) {
				// remove current event listeners
				element.removeEventListener('touchstart', events, false);
				element.removeEventListener('webkitTransitionEnd', events, false);
				element.removeEventListener('msTransitionEnd', events, false);
				element.removeEventListener('oTransitionEnd', events, false);
				element.removeEventListener('otransitionend', events, false);
				element.removeEventListener('transitionend', events, false);
				window.removeEventListener('resize', events, false);
			}
			else {
				window.onresize = null;
			}

		}
	}
}


if ( window.jQuery || window.Zepto ) {
	(function($) {
		$.fn.Swipe = function(params) {
			return this.each(function() {
				$(this).data('Swipe', new Swipe($(this)[0], params));
			});
		}
	})( window.jQuery || window.Zepto )
}
